The E. coli transcription factor GrlA is regulated by subcellular compartmentalization and activated in response to mechanical stimuli

Significance EHEC bacteria have been implicated in numerous outbreaks of serious foodborne illnesses. EHEC activates virulence factors that promote gut colonization upon host ingestion by relying upon the sensation of mechanical stimuli created when bacteria adhere to intestinal tissue and when fluid flows past the bacterial membrane following adhesion. We found that the EHEC regulator GrlA activates virulence genes in response to mechanosensation. In planktonic bacteria, GrlA is membrane bound and physically separated from its DNA targets. When EHEC is mechanically stimulated, GrlA is released from the membrane into the cytoplasm, where it can bind and activate virulence gene promoters. This regulatory mechanism allows EHEC to rapidly adapt to the highly dynamic mechanics of the host intestine and successfully colonize.